Mr Rahman's legal team have notified the home secretary they intend to sue
A Briton held on suspicion of terrorism in Bangladesh is to sue Home Secretary Jacqui Smith, alleging she allowed his torture, the Home Office has confirmed.
Former civil servant Jamil Rahman, who grew up in south Wales, claims he was interrogated by MI5 officers in between beatings by Bangladesh security forces.
He gave false confessions, including that he masterminded the 2005 terror attacks on London, Mr Rahman says.
The Home Office says British security forces neither condone nor use torture.
A Home Office spokeswoman said Mr Rahman's legal team had written to the home secretary, who would respond "in due course".
'Above the law'
According to the Guardian newspaper, Mr Rahman, 31, is suing in relation to assault, unlawful arrest, and false imprisonment.
He said he was detained in December 2005 by the DGFI - one of Bangladesh's intelligence agencies - and was stripped and beaten.
He claimed he made the tape-recorded confessions before being questioned by two men calling themselves Andrew and Liam who said they were from MI5.
When he told them the confessions were false, they took a break and he was beaten again before their questioning resumed, Mr Rahman claims.
He says at one point his wife was held in the next room, and Bangladeshi officers threatened to rape her.
He was eventually released, only to be questioned several more times over the next two years by MI5 and detectives from Scotland Yard, he says.
The Guardian says Mr Rahman's lawyers claim to have evidence including eyewitness testimony and medical information.
The legal charity Reprieve claimed the government was guilty of "torture through the back door" and urged it to publish its rules on intelligence gathering.
Director Clive Stafford Smith said by maintaining secrecy, the government placed the secret services above the law.
"Crimes have been committed in the name of the British people, and continue to be covered up," he said.
Renditions investigator Clara Gutteridge added: "The only difference between this practice and what happens at Guantanamo Bay is that this torture is decentralised and outsourced."
Mr Rahman, who settled in Bangladesh in 2005, returned to the UK last year.
He launched his legal action after his wife and daughter were able to join him in Britain.
The Home Office spokeswoman said: "The government unreservedly condemns the use of torture as a matter of fundamental principle and works hard with its international partners to eradicate this abhorrent practice worldwide.
"The security and intelligence agencies do not participate in, solicit, encourage or condone the use of torture or inhumane or degrading treatment."